Power source, power failure detection apparatus, and image forming apparatus

• US 9,270,163 B2
• Filed: 01/29/2013
• Issued: 02/23/2016
• Est. Priority Date: 01/31/2012
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Shimura, Yasuhiro
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): AHMED, YUSEF A
• Application Number:
  US13/752,772
• Publication Number:
  US 20130195497A1
• Time in Patent Office: 1,120 Days
• Field of Search: 323271-275, 323282-285, 323/207, 363/53, 363 5608- 5611, 363/84, 363/126, 363/89, 399/33, 399/37, 399 69- 70, 399/88
• US Class Current: 1/1
• CPC Class Codes: G03G 15/80 Details relating to power supplies, circuits boards, electrical connections
• CPC Class Codes: H02J 9/005 using a power saving mode for copiers G03G15/5004
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

A power source includes a rectifying unit configured to full-wave rectify an AC voltage to be input, a first and second converter configured to convert the voltage rectified by the rectifying unit, a zero cross detection unit configured to detect a zero cross of the AC voltage, a voltage detection unit configured to detect the AC voltage, a first capacitance element connected across a potential after being subjected to rectification by the rectifying unit and a ground, a first discharging resistor configured to discharge electric charges charged in the first capacitance element, a first switch unit configured to cut off a current flowing to the first discharging resistor and a stopping unit configured, in a case where the AC voltage is detected by the voltage detection unit and the detected voltage is smaller than a threshold value, to stop the operation of the second converter.

Claims

1. A power source comprising:

a rectifying unit configured to full-wave rectify an alternating current (AC) voltage to be input;

a first converter configured to convert a rectified voltage from the rectifying unit to a first voltage;

a zero cross detection unit configured to detect a zero cross of the AC voltage and supplied with the first voltage;

a first capacitance element connected between an output side of the rectified voltage from the rectifying unit and a ground;

a first discharging resistor connected to an input side of the AC voltage with respect to the rectifying unit and configured to discharge electric charges charged in the first capacitance element;

a voltage detection unit connected to the first discharging resistor and configured to detect the AC voltage and output a signal corresponding to the detected AC voltage;

a first switch unit configured to switch a signal supplied to the voltage detection unit and supplied with the first voltage;

a second capacitance element connected to an input side of the AC voltage with respect to the rectifying unit and across two lines to which the AC voltage is supplied; and

a second discharging resistor connected between an input side of the AC voltage with respect to the rectifying unit and the zero cross detection unit and configured to discharge electric charges charged in the second capacitance element,

wherein the zero cross detection unit detects the zero cross of the AC voltage using a current flowing to the second discharging resistor and wherein the first discharging resistor is lower in resistance than the second discharging resistor; and

wherein in a case where the power source is in an energy saving state, supply of the first voltage to the zero cross detection unit and the first switch unit is shut off.

2. The power source according to claim 1, further comprising:

a second converter configured to convert a voltage rectified by the rectifying unit to a second voltage, wherein

the second converter is connected in parallel to the first converter; and

in a case where the first switch unit is in off state, the operation of the second converter is stopped according to the signal output from the voltage detection unit.

3. The power source according to claim 1, wherein if the zero cross detection unit cannot detect the zero cross of the AC voltage for at least a predetermined time period input of the AC voltage being shut off is detected.

4. The power source according to claim 1, wherein if the voltage detection unit detects a voltage lower than the threshold value, input of the AC voltage being shut off is detected.

5. An image forming apparatus comprising:

an image forming unit configured to form an image;

a power source configured to supply power to the image forming unit, the power source comprising;

a rectifying unit configured to full-wave rectify an alternating current (AC) voltage to be input;

a first converter configured to convert a rectified voltage from the rectifying unit to a first voltage;

a zero cross detection unit configured to detect a zero cross of the AC voltage and supplied with the first voltage;

a first capacitance element connected between an output side of the rectified voltage of the rectifying unit and a ground;

a first discharging resistor connected to an input side of the AC voltage with respect to the rectifying unit and configured to discharge electric charges charged in the first capacitance element;

a voltage detection unit connected to the first discharging resistor and configured to detect the AC voltage and output a signal corresponding to the detected AC voltage; and

a first switch unit configured to switch a signal input to the voltage detection unit and supplied with the first voltage;

a second capacitance element connected to an input side of the AC voltage with respect to the rectifying unit and across two lines to which the AC voltage is supplied; and

a second discharging resistor connected between an input side of the AC voltage with respect to the rectifying unit and the zero cross detection unit and configured to discharge electric charges charged in the second capacitance element,

wherein the zero cross detection unit detects the zero cross of the AC voltage using a current flowing to the second discharging resistor and wherein the first discharging resistor is lower in resistance than the second discharging resistor,

wherein in a case where the power source is in an energy saving state, supply of the first voltage to the zero cross detection unit and the first switch unit is shut off.

6. The imaging forming apparatus according to claim 5, further comprising:

a second converter configured to convert a voltage rectified by the rectifying unit to a second voltage, wherein

the image forming unit comprises a fixing unit configured to fix an image formed on a recording material; and

wherein the power source supplies the AC voltage to the fixing unit.

7. The imaging forming apparatus according to claim 5, wherein if the zero cross detection unit cannot detect the zero cross of the AC voltage for at least a predetermined time period, input of the AC voltage being shut off is detected.

8. The imaging forming apparatus according to claim 5, wherein if the voltage detection unit detects a voltage lower than the threshold value, input of the AC voltage being shut off is detected.

9. A power failure detection apparatus comprising:

a zero cross detection unit configured to detect the zero cross of AC voltage to be input;

a first capacitance element connected between an output side of a rectified voltage of the rectifying unit for rectifying the AC voltage and a ground;

a first discharging resistor connected to an input side of the AC voltage with respect to the rectifying unit and configured to discharge electric charges charged in the first capacitance element;

a voltage detection unit configured to detect the value of the AC voltage;

a first switch unit connected between the first discharging resistor and the voltage detection unit and configured to switch a signal supplied to the voltage detection unit;

a second capacitance element connected across two lines to which the AC voltage is supplied;

a first discharge path in a case where the electric charges charged in the second capacitance element are positive; and

a second discharge path in a case where the electric charges charged in the second capacitance element are negative,

wherein the first discharging resistor is used as the first discharge path, a second discharging resistor is used as the second discharge path, the zero cross detection unit detects the zero cross using a current flowing to the second discharging resistor, and the first discharging resistor is lower in resistance than the second discharging resistor.

10. The power failure detection apparatus according to claim 9,

wherein the voltage detection unit includes a charging resistor, a charging capacitor and a discharge unit for discharging the charging capacitor,

wherein the charge of the charging capacitor using the charging resistor and the discharge of the charging capacitor using the discharge unit are repeated every half cycle of the AC voltage, and

wherein the voltage detection unit turns on the first switch if the voltage of the charging capacitor increases and becomes equal to or larger than a threshold value.

11. The power failure detection apparatus according to claim 10, wherein the charging capacitor is discharged using the zero cross detection unit.

12. The power failure detection apparatus according to claim 9, further comprising:

a current fuse provided at the back of the second capacitance element; and

a third discharge path provided between the current fuse and the second capacitance element, wherein the third discharge path discharges electric charges in the second capacitance element if the current fuse blows out.